Introducing a catheter into the vasculature is a common medical technique, but one that is prone to severe complications. To insert a catheter, an access site (i.e., an incision) must be made in an arterial wall. Traditionally, a catheter is introduced using the Seldinger technique, named for a Swedish radiologist who invented the procedure in 1953. In the Seldinger technique, a blood vessel is punctured with a hollow needle. Venous placement is confirmed by monitoring pulsatile blood flow through the needle. When that flow of blood confirms that the needle has accessed the vessel, a round-tipped guidewire is advanced through the lumen of the needle into the vessel. The guidewire is held in place while the needle is withdrawn. Generally the cutaneous puncture site is widened with a scalpel to create a larger hole for the catheter to pass through. A dilator may be used to enlarge the access site as needed. Next a catheter sheath is threaded onto the guidewire. The catheter is passed over the guidewire using a twisting motion to advance it into the vessel, and the catheter is advanced to its final indwelling position. The guidewire is then withdrawn through the catheter, leaving the catheter in place in the vessel.
The Seldinger technique involves several moving parts and placement steps. Each step requires time and precision, and each part must be sterile to avoid infection to the patient. Thus, many risks are involved. For example, complications may arise when a part is withdrawn prematurely, for example the guidewire being inadvertently pulled out with the needle. Alternatively, guidewire embolism can occur when the guidewire gets lost in the vein while the clinician is pushing the dilator or the sheath over it. Creating a suitable access site often involves multiple attempts, each with an associated risk of vein puncture and hematoma. Access site complications are the most common type of complication after diagnostic and percutaneous coronary intervention, and complication rates are even higher for procedures involving large arterial sheaths for device delivery such as in aortic valve replacement. Frequent complications include air embolism, bloodstream infection, bleeding, contamination, and loss of cannulation. Those complications increase patient morbidity and mortality, lengthen hospital stays, and increase healthcare costs.